Add ps command to asynqmon

tools/asynqmon/cmd/root.go

@@ -6,7 +6,10 @@ package cmd
 
 import (
 	"fmt"
+	"io"
 	"os"
+	"strings"
+	"text/tabwriter"
 
 	"github.com/spf13/cobra"
 
@@ -81,3 +84,36 @@ func initConfig() {
 		fmt.Println("Using config file:", viper.ConfigFileUsed())
 	}
 }
+
+// printTable is a helper function to print data in table format.
+//
+// cols is a list of headers and printRow specifies how to print rows.
+//
+// Example:
+// type User struct {
+//     Name string
+//     Addr string
+//     Age  int
+// }
+// data := []*User{{"user1", "addr1", 24}, {"user2", "addr2", 42}, ...}
+// cols := []string{"Name", "Addr", "Age"}
+// printRows := func(w io.Writer, tmpl string) {
+//     for _, u := range data {
+//         fmt.Fprintf(w, tmpl, u.Name, u.Addr, u.Age)
+//     }
+// }
+// printTable(cols, printRows)
+func printTable(cols []string, printRows func(w io.Writer, tmpl string)) {
+	format := strings.Repeat("%v\t", len(cols)) + "\n"
+	tw := new(tabwriter.Writer).Init(os.Stdout, 0, 8, 2, ' ', 0)
+	var headers []interface{}
+	var seps []interface{}
+	for _, name := range cols {
+		headers = append(headers, name)
+		seps = append(seps, strings.Repeat("-", len(name)))
+	}
+	fmt.Fprintf(tw, format, headers...)
+	fmt.Fprintf(tw, format, seps...)
+	printRows(tw, format)
+	tw.Flush()
+}